Bsi bs en 16197 2012

BS EN 16197:2012

BSI Standards Publication

Fertilizers — Determination
of magnesium by atomic
absorption spectrometry


BS EN 16197:2012

BRITISH STANDARD

National foreword
This British Standard is the UK implementation of EN 16197:2012.
It supersedes DD CEN/TS 16197:2011, which is withdrawn.
The UK participation in its preparation was entrusted to
Technical Committee CII/37, Fertilisers and related chemicals.
A list of organizations represented on this committee can be
obtained on request to its secretary.
This publication does not purport to include all the necessary
provisions of a contract. Users are responsible for its correct
application.
© The British Standards Institution 2012.
Published by BSI Standards Limited 2012.
ISBN 978 0 580 78184 1
ICS 65.080
Compliance with a British Standard cannot confer immunity
from legal obligations.
This British Standard was published under the authority of the
Standards Policy and Strategy Committee on 31 December 2012.

Amendments issued since publication
Date

Text affected


BS EN 16197:2012

EN 16197

EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM

November 2012

ICS 65.080

Supersedes CEN/TS 16197:2011

English Version

Fertilizers - Determination of magnesium by atomic absorption
spectrometry
Engrais - Dosage du magnésium par spectrométrie
d'absorption atomique

Düngemittel - Bestimmung von Magnesium mit
Atomabsorptionsspektrometrie

This European Standard was approved by CEN on 6 October 2012.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2012 CEN

All rights of exploitation in any form and by any means reserved
worldwide for CEN national Members.

Ref. No. EN 16197:2012: E


BS EN 16197:2012
EN 16197:2012 (E)

Contents

Page

Foreword ..............................................................................................................................................................3
1

Scope ......................................................................................................................................................4

2

Normative references ............................................................................................................................4

3

Terms and definitions ...........................................................................................................................4

4

Principle ..................................................................................................................................................4

5

Sampling .................................................................................................................................................5

6

Reagents .................................................................................................................................................5

7

Apparatus ...............................................................................................................................................5

8

Preparation of the extraction solution .................................................................................................5

9
9.1
9.2
9.3
9.4

Procedure ...............................................................................................................................................6
Preparation of the test solution............................................................................................................6
Preparation of the blank solution.........................................................................................................6
Preparation of the calibration solutions ..............................................................................................6
Measurement ..........................................................................................................................................6

10

Calculation and expression of the result ............................................................................................7

11
11.1
11.2
11.3

Precision .................................................................................................................................................7
Inter-laboratory test ...............................................................................................................................7
Repeatability...........................................................................................................................................7

Reproducibility .......................................................................................................................................7

12

Test report ..............................................................................................................................................8

Annex A (informative) Statistical results of the inter-laboratory test ............................................................9
Bibliography ..................................................................................................................................................... 11

2


BS EN 16197:2012
EN 16197:2012 (E)

Foreword
This document (EN 16197:2012) has been prepared by Technical Committee CEN/TC 260 “Fertilizers and
liming materials”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by May 2013, and conflicting national standards shall be withdrawn at the
latest by May 2013.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes CEN/TS 16197:2011.
The following changes have been made to the former edition:
a) the CEN Technical Specification has been adopted as a European Standard;
b) the document has been editorially revised.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following

countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

3


BS EN 16197:2012
EN 16197:2012 (E)

1

Scope

This European Standard specifies a method for the determination of the magnesium content in fertilizer
extracts using atomic absorption spectrometry (AAS).
This method is applicable to EC fertilizer extracts obtained according to EN 15960 and EN 15961, for which a
declaration of the total magnesium and/or water soluble magnesium content is required, with the exceptions of
the following fertilizers according to [4], Annex I D relating to secondary nutrients:


type 4 (kieserite);



type 5 (magnesium sulfate) and type 5.1 (magnesium sulfate solution);

and with the exception of the following fertilizer listed in [4], Annex I A.3 relating to potassic fertilizers:


type 7 (kieserite with potassium sulfate)

to which [4], method 8.8, applies.
NOTE

Method 8.8 is covered by EN 16198 [2].

The method applies to all fertilizer extracts containing elements in quantities that might interfere with the
complexometric determination of magnesium.

2

Normative references

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
EN 1482-2, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample
preparation
EN 12944-1:1999, Fertilizers and liming materials and soil improvers — Vocabulary — Part 1: General terms
EN 12944-2:1999, Fertilizers and liming materials and soil improvers — Vocabulary — Part 2: Terms relating
to fertilizers
EN 15960, Fertilizers — Extraction of total calcium, total magnesium, total sodium and total sulfur in the forms
of sulfates
EN 15961, Fertilizers — Extraction of water soluble calcium, magnesium, sodium and sulfur in the form of
sulfates

3

Terms and definitions

For the purposes of this document, the terms and definitions given in EN 12944-1:1999 and EN 12944-2:1999
apply.

4

Principle

Determination of magnesium by atomic absorption spectrometry (AAS) after appropriate dilution of the extract.

4


BS EN 16197:2012
EN 16197:2012 (E)

5

Sampling

Sampling is not part of the method specified in this document. A recommended sampling method is given in
EN 1482-1 [1].
Sample preparation shall be carried out in accordance with EN 1482-2. Grinding of the laboratory sample is
recommended for homogeneity reasons.

6

Reagents

6.1

Hydrochloric acid solution, c = 1 mol/l.

6.2

Hydrochloric acid solution, c = 0,5 mol/l.

6.3

Standard solution of magnesium, ρ = 1,00 mg/ml.

6.3.1

Preferably use a commercially available certified stock solution of magnesium.

6.3.2 Dissolve 1,013 g of magnesium sulfate (MgSO4, 7H2O) in hydrochloric acid solution (6.2), transfer
quantitatively into a graduated flask (7.3) and make up the volume with the same acid and mix.
6.3.3

Weigh 1,658 g of magnesium oxide (MgO), previously calcined to remove all traces of carbonation.

Place in a beaker with 100 ml of water and 120 ml of hydrochloric acid (6.1). When it has dissolved, decant
quantitatively into a graduated flask (7.5). Make up the volume by adding and mix.
The concentration of magnesium in the stock solution shall be checked on a regular basis.
6.4

Strontium chloride solution.

Dissolve 75 g of strontium chloride (SrCl2 6H2O) in a hydrochloric acid solution (6.2) and make up to 500 ml

with the same acid solution.

7

Apparatus

7.1

Spectrometer, fitted for atomic absorption, with a magnesium lamp, set at 285,2 nm.

7.2

Air-acetylene flame.

7.3

100 ml graduated flask.

7.4

200 ml graduated flask.

7.5

1 000 ml graduated flask.

8

Preparation of the extraction solution

The extraction solutions shall be prepared according to EN 15960 or EN 15961.

5


BS EN 16197:2012
EN 16197:2012 (E)

9

Procedure

9.1

Preparation of the test solution

9.1.1 If the fertilizer has a declared magnesium (Mg) content of more than 6 % (i.e. 10 % as M g O), take
25 ml (V1) of the extraction solution (see Clause 8). Transfer into a graduated flask (7.3), and make up to
volume with water and mix. The dilution factor is D1 = 100/V1.
9.1.2 Using a pipette, take 10 ml of the extraction solution (see Clause 8) or the solution (9.1.1). Transfer
into a graduated flask (7.4). Make up to volume with hydrochloric acid solution (6.2) and mix. The dilution
factor is 200/10.
9.1.3 Dilute this solution (9.1.2) with hydrochloric acid solution (6.2) so as to obtain a concentration in the
optimum working field of the spectrometer (7.1). V2 is the volume of the sample in 100 ml. The dilution factor is
D2 = 100/V2.
9.1.4

9.2

The final solution should contain 10 % (volume fraction) of the strontium chloride solution (6.4).

Preparation of the blank solution

Prepare a blank solution by repeating the whole procedure from the extraction according to EN 15960 or
EN 15961, omitting only the test sample of fertilizer.

9.3

Preparation of the calibration solutions

By diluting the standard solution (6.3) with the hydrochloric acid (6.2), prepare at least five calibration solutions
of increasing concentration within the optimum measuring range of the apparatus (7.1).
These solutions should contain 10 % (volume fraction) of the strontium chloride solution (6.4).

9.4

Measurement

Set up the atomic absorption spectrometer (7.1) according to the manufacturer's instructions at a wavelength
of 285,2 nm.
Spray, successively, the calibration solutions (9.3), the sample solution (9.1) and the blank solution (9.2),
washing the instrument through with the solution to be measured next. Repeat this operation three times. Plot
the calibration curve using the mean absorbencies of each of the calibrations (9.3) as the ordinates and the
corresponding mass concentration of magnesium in micrograms per millilitre as the abscissas. Determine the
concentration of magnesium in the sample (9.1), Xs and blank (9.2), Xb, by reference to the calibration curve.

6


BS EN 16197:2012

EN 16197:2012 (E)

10 Calculation and expression of the result
Calculate the amount of magnesium (Mg) or magnesium oxide (MgO) in the sample by reference to the
calibration solutions and taking into consideration the blank.
Calculate the magnesium content in the fertilizer, wMg, as a mass fraction in percent according to Formula (1).

wMg =

( X S − X b ) D1 (200/10 ) D2 500 × 100
1 000 × 1 000 M

(1)

where
Xs

is the concentration of the solution to be analysed recorded on the calibration curve, in micrograms
per millilitre;

Xb is the concentration of the blank solution as recorded on the calibration curve, in micrograms per
millilitre;
D1 is the dilution factor when the solution is diluted (9.1.1):


it is equal to 4 if 25 ml are taken;



it is equal to 1 when the solution is not diluted;

D2 is the dilution factor (9.1.3);
M

is the mass, in grams, of the test sample at the time of extraction.

MgO (%) = Mg (%)/0,6

11 Precision
11.1 Inter-laboratory test
Repeated inter-laboratory tests have been carried out in 2007 and 2009 with different numbers of participating
laboratories and several different samples (see Table A.1 to Table A.4). Repeatability and reproducibility were
calculated according to ISO 5725-2.
The values derived from these inter-laboratory tests may not be applicable to concentration ranges and matrices
other than those given in Annex A.

11.2 Repeatability
The absolute difference between two independent single test results, obtained with the same method on
identical test material in the same laboratory by the same operator using the same equipment within a short
interval of time, will in not more than 5 % of the cases exceed the values of r given in Table 1 and Table 2.

11.3 Reproducibility
The absolute difference between two single test results, obtained with the same method on identical test
material in different laboratories by different operators using different equipment, will in not more than 5 % of
the cases exceed values of R given in Table 1 and Table 2.

7


BS EN 16197:2012

EN 16197:2012 (E)

Table 1 — Results ring test 2007
Sample

Extraction method

x
%

r
%

R
%

EN 15960

4,75

0,15

0,82

EN 15961

1,83

0,25

1,18

EN 15960

6,28

0,25

0,80

EN 15961

6,05

0,20

0,83

EN 15960

3,38

0,13

0,74

EN 15961

3,04

0,13

0,62

CAN

KALI ROH

NPK2:12-11-18+2+8

Table 2 — Results ring test 2009
Sample

Extraction method

x
%

r
%

R
%

EN 15960

4,38

0,11

1,65

EN 15961

2,38

0,30

3,23

EN 15960

1,88

0,08

0,32

EN 15961

1,58

0,08

0,52

CAN

NPK:12-12-17S+2

12 Test report
The test report shall contain at least the following information:
a)

all information necessary for the complete identification of the sample;

b)

the test method used with reference to this document;

c)

the method of preparation of the extraction solution (EN 15960 or EN 15961);

d)

the test results obtained;

e)

date of sampling and sampling procedure (if known);

f)

date when the analysis was finished;

g)

whether the requirement of the repeatability limit has been fulfilled;

h)

8

all operating details not specified in this document, or regarded as optional, together with details of
any incidents occurred when performing the method, which might have influenced the test result(s).


BS EN 16197:2012
EN 16197:2012 (E)

Annex A
(informative)
Statistical results of the inter-laboratory test

The precision of the method was established in 2007 and in 2009 by Working Group 7 “Chemical analysis” of
CEN/TC 260 “Fertilizers and liming materials” in several inter-laboratory tests evaluated in accordance with
ISO 5725-2. The statistical results are given in Table A.1 to Table A.4.
Table A.1 — Statistical results of the inter-laboratory test in 2007 – Extraction method EN 15960
Parameter

Sample
CAN

KALI ROH

NPK2:12-11-18+2+8

Number of participating laboratories

13

14

14

Number of laboratories after elimination
of outliers (accepted test results)

13

12

12

4,75

6,28

3,38

Repeatability standard deviation sr (%)

0,05

0,09

0,05

RSDr (%)

1,1

1,4

1,4

Repeatability limit r (%)

0,15

0,25

0,13

Reproducibility standard deviation sR
(%)

0,29

0,29

0,27

RSDR (%)

6,2

4,6

7,9

Reproducibility limit R (%)

0,82

0,80

0,74

Mean value

x (%)

Table A.2 — Statistical results of the inter-laboratory test in 2007 – Extraction method EN 15961
Parameter

Sample
CAN

KALI ROH

NPK2:12-11-18+2+8

Number of participating laboratories

13

14

14

Number of laboratories after elimination
of outliers (accepted test results)

12

14

14

1,83

6,05

3,04

Repeatability standard deviation sr (%)

0,09

0,07

0,05

RSDr (%)

5,0

1,2

1,6

Repeatability limit r (%)

0,25

0,20

0,13

Reproducibility standard deviation sR
(%)

0,42

0,30

0,22

RSDR (%)

23,0

4,9

7,2

Reproducibility limit R (%)

1,18

0,83

0,62

Mean value

x (%)

9


BS EN 16197:2012
EN 16197:2012 (E)

Table A.3 — Statistical results of the inter-laboratory test in 2009 – Extraction method EN 15960
Parameter

Sample
CAN

NPK:12-12-17S+2

Number of participating laboratories

10

10

Number of laboratories after elimination
of outliers (accepted test results)

8

10

4,38

1,88

Repeatability standard deviation sr (%)

0,04

0,03

RSDr (%)

0,9

1,5

Repeatability limit r (%)

0,11

0,08

Reproducibility standard deviation sR

(%)

0,59

0,12

RSDR (%)

13,5

6,2

Reproducibility limit R (%)

1,65

0,32

Mean value

x (%)

Table A.4 — Statistical results of the inter-laboratory test in 2009 – Extraction method EN 15961
Parameter

CAN

NPK:12-12-17S+2

Number of participating laboratories

9

9

Number of laboratories after elimination
of outliers (accepted test results)

8

9

2,38

1,58

Repeatability standard deviation sr (%)

0,11

0,03

RSDr (%)

4,0

1,8

Repeatability limit r (%)

0,30

0,08

Reproducibility standard deviation sR
(%)

1,15

0,18

RSDR (%)

48,0

11,6

Reproducibility limit R (%)

3,23

0,52

Mean value

10

Sample

x (%)

BS EN 16197:2012
EN 16197:2012 (E)

Bibliography

[1]

EN 1482-1, Fertilizers and liming materials — Sampling and sample preparation — Part 1: Sampling

[2]

EN 16198, Fertilizers ― Determination of magnesium by complexometry

[3]

ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic
method for the determination of repeatability and reproducibility of a standard measurement method

[4]

Regulation (EC) No 2003/2003 of the European Parliament and of the Council of 13 October 2003
relating to fertilisers, Official Journal L 304, 21/11/2003, p. 0001-0194, Annex I and Annex IV, method
8.7, method 8.8

11


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